Gordon Brown visited a school in the melting pot that is east London yesterday to promote the elusive concept of modern Britishness. It is one of the chancellor's favourite themes, not least because he knows it matters to his own future as well as everyone else's.

In a week which has seen chilling convictions for racial murder in Glasgow, and other tensions along familiar cultural and religious faultlines (not to mention yesterday's cautious Tory foray into immigration policy), Mr Brown remains a dogged optimist, his good eye on the long term, not tomorrow's headlines. For a Scots unionist, keen to maintain the four-nation British state against centrifugal localism (51% of Scots backed independence in a recent poll) on both sides of the border, the prime minister-in-waiting-for-ages is always on the search for new expressions of that union. "Finding other things that unite us, that's the key, isn't it?" he said yesterday. By which he means values and institutions, the NHS, the BBC or the 2012 Olympics, to be staged in a city where, on some estimates, nearly 300 languages are regularly spoken. He could have added "Gordon Brown", as he must convince English voters on the point next election day.

At Langdon Park school in Tower Hamlets he did quite well among GCSE students from many backgrounds. "Freedom of speech" and "free health care", said one. "Charity", said another. "Fish and chips" and Grenada-born Private Johnson Beharry VC (the latest addition to the 100 Top Black Britons) were also cited as British symbols.

One lad who may go far added: "We are always ready to embrace other countries, we're proud to have British Asians and black British people." That is not the message all Labour MPs pick up. In recent days two have told me of strong anti-Polish feeling (just for starters) in large provincial towns. Pressure on public services, not to mention downward pressure on wages, are a real issue. But Mr Brown was quick to fold the students' remarks into his vision of a Britain committed to tolerance, openness and debt relief.

It is a wholesome vision and has some bearing on reality. In past speeches Mr Brown has quoted Orwell, Burke, the Leveller, Colonel Rainborough and his fellow-Kirkaldy boy Adam Smith to pick a delicate path between European statist traditions and American anti-statism.

Liberty, fairness, responsibility and internationalism are the enduring hallmarks of Britishness, he likes to say, raised as he was on tales of David Livingstone. Those values have endured long after the transient concept of Britishness built on Protestantism, empire, race and xenophobia have receded, he argues.

On a good day it sounds do-able and consistent with Brown's vision of an outward-looking Britain, facing up to global challenges. But critics on the political right hark nostalgically back to the empire's civilising mission, on the left to its arrogance and many crimes. One hates Europe, the other hates America.